JPS6325333B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a dry developer for electrophotography, in which a high-resistance element is inserted between a conductive developing sleeve and ground, or an electrically insulating carrier is used in the developing sleeve. The present invention relates to a magnetic toner for electrophotography with which good images can be obtained.

Conventionally, in electrophotography, an electrostatic latent image is formed on a photoconductor such as a selenium or bad lead oxide photoreceptor, and a carrier such as a glass sphere or iron powder and an insulating colored fine powder toner are mixed on the surface of the latent image. Then, the toner is brought into contact with a triboelectrically charged developer to perform electrostatic development. Either record this directly on zinc oxide photosensitive paper or electrostatic recording paper, or
Alternatively, a method is mainly employed in which an image is formed on a photoconductive master photoreceptor, a transfer sheet is placed on top of the image, and the image is transferred by applying an electric field.

The developer used together with the carrier is often used as a dry developer for electrophotography and is called a two-component developer. In contrast, in recent years, magnetic toner that does not use a carrier has been attracting attention for the purpose of simplifying and downsizing electronic copying devices. Magnetic toner contains magnetic powder such as magnetite (Fe ₃ O ₄ ) in the toner, and conductive particles such as carbon black are added inside or on the surface of the toner to control the conductivity of the toner. When using with conductivity higher than 10 ^-7 cm ^-1 ,
It is used for direct development of the above-mentioned photosensitive recording papers. Furthermore, when the conductivity is lowered to less than 10 ^-7 cm ^-1 , it is used for electric field transfer from a photoreceptor to a transfer sheet.

The magnetic toner of the present invention relates to the latter type of magnetic toner for transfer, and aims to improve the development and transfer properties of conventional magnetic toner for transfer and obtain a high-quality transferred image. In particular, in the conventional developing method of grounding the conductive sleeve of the developing magnet roll, when a high resistance material of 1MΩ or more is inserted between the sleeve and the ground, or when an electrically insulating carrier is used for the sleeve. The purpose is to obtain good images when

The development mechanism of magnetic toner has high conductivity (conductivity >
10 ^-7 cm ^-1 ) has been elucidated, and a conductive path is formed between the toner particles and the conductive sleeve, and a charge of opposite polarity to the electrostatic charge on the photoreceptor is transferred from the grounded conductive sleeve. is injected, the toner is charged, and development is performed. This method is also applied to toner with low conductivity (conductivity <10 ^-7 cm ^-1 ), but since the toner has low conductivity, the developing machine is not suitable for toner with high conductivity. It is thought that not only the induced charging such as the above, but also the internal polarization of the toner, the toner and the sleeve, the photoreceptor, and the frictional charging between the toners are involved in a complicated manner.
In conventional toners with low conductivity, the amount of conductive particles such as carbon black added is minimized to lower the conductivity of the toner, but as a developing method, the conductive sleeve is completely grounded. It was necessary to use it. If the sleeve is not grounded,
Either no image is obtained, or even if an image is obtained, the development is so uneven that it is not practical. On the other hand, it is very difficult to completely ground the conductive sleeve when the sleeve rotates, and the structure must be complicated. Also, depending on the materials (magnetic powder, fixing resin, pigments, dyes, and other additives) and composition used in low-conductivity toners, the method of completely grounding the conductive sleeve may be Since the electric field strength between the bodies increases, a large amount of toner particles adhere to the photoreceptor, resulting in an image with a lot of fog, making it an unstable method for image production.

Due to the above circumstances, when using a conductive sleeve, there are toners that can be developed well even if the sleeve is not completely grounded, that is, a high-resistance material is inserted between the sleeve and the ground, or a sleeve that is completely electrically insulated. There has been a long-awaited need for a toner that can be developed using a specific carrier.

The toner of the present invention was developed in view of the above situation, and even if the conductive sleeve is incompletely grounded, that is, even if a high-resistance element is inserted between the sleeve and the ground, the image will remain unchanged. Good results. Furthermore, the toner is intended to provide relatively good images even when an electrically insulating carrier is used as the sleeve.

The toner of the present invention is characterized by the presence of non-magnetic fine particles [A] which are smaller than the toner particles and can be triboelectrically charged by contact with the toner particles, and non-magnetic conductive particles [B] on the surface of the toner particles. from 0.01 to toner particles by weight within the range of [B] or more.
It is to be maintained at a ratio of 3%, preferably 0.1 to 1%.

That is, in the toner of the present invention, the toner particles rub against the nonmagnetic fine particles [A] as they roll on the developing magnet roll sleeve, and are triboelectrically charged with each other, generating triboelectricity at the interface. As a result, the toner particles [A] remain electrostatically attached to the surface due to the electrostatic attraction force caused by friction.
As the developing machine rotates, an electric field is created between the charge on the photoreceptor and the sleeve. In this electric field, electric polarization occurs between some toner particles through the conductive fine particles [B] on the surface of the toner particles.
That is, charge transfer occurs through the conductive fine particles [B] on the toner surface, and the toner particles are charged.
The mobility of the charge, that is, the speed of electric polarization, is accelerated by the frictional electricity between the toner particles and the fine particles [A], and eventually the toner particles near the charge on the photoreceptor become polarized opposite to the charge. The charged toner particles overcome the magnetic force and adhere to the photoreceptor. When an electrically insulating carrier is used as a sleeve,
It is believed that development of the photoreceptor is performed based on the above-described development mechanism. On the other hand, when the conductive sleeve is grounded through a high resistance object,
It is thought that a polarizing charge is injected into the toner, which is different from the charge on the photoreceptor, and the toner itself is charged and development is performed. Even in this case, if the above-mentioned fine particles [A] are attached to the surface of the toner due to frictional charging and retain static electricity due to friction, and conductive fine particles [B] are present on the toner surface, It is thought that the charge is more likely to be injected from the sleeve to the toner, the toner is more likely to be charged, and development is easier to be performed.

The toner of the present invention based on the above findings is characterized by holding both triboelectrically charged fine particles [A] and conductive fine particles [B] on the surface of the toner particles. is something new that has never existed before.

The toner particles of the present invention are composed of at least ferromagnetic fine particles and a thermoplastic resin.
Ferromagnetic particles are substances that are extremely strongly magnetized in the direction of a magnetic field, such as alloys or compounds containing ferromagnetic elements such as ferrite, magnetite, iron, cobalt, nickel, etc. Various alloys that exhibit ferromagnetism through treatment can also be effectively used. These ferromagnetic materials have an average particle size of 5~
Since it is contained in toner particles classified into 40 μm, preferably 5 to 20 μm, the average particle size is 0.05 to 0.05 μm.
5 μm, preferably 0.1 to 0.5 μm. These ferromagnetic materials have a conductivity of about 10 ^-6 cm ^-1 , and if they are well dispersed in the toner, the ferromagnetic particles will form a conductive path in the toner. However, since there is a risk of increasing the conductivity of the toner more than necessary, it is also effective to coat the surface of the magnetic powder used with an electrically insulating resin, if necessary, in order to lower the conductivity of the toner of the present invention. be. The amount of the ferromagnetic fine particles added is preferably in the range of 40 to 70% by weight. Within this range, the greater the amount added, the sharper the image, and the better the image quality.

The thermoplastic resin is essential for fixing the toner to the paper surface. Depending on the fixing method,
Various resin materials are used. When fixing images using a pressure roll, various waxes, higher fatty acids or metal salts of higher fatty acids, higher fatty acid derivatives, higher fatty acid amides, acrylic acid or Copolymerized oligomer of methacrylic acid and Changzhen alkyl acrylate Changzhen alkyl methacrylate, polyolefin, ethylene-vinyl acetate copolymer, ethylene-vinyl alkyl ether copolymer, areic anhydride copolymer, petroleum residue,
Examples include rubbers and fatty acid-modified epoxy resins. Among these, waxes are particularly effectively used.

When the fixing method is an open fixing method or a heated roll fixing method, various thermoplastic resins as described below can be used depending on the fixing temperature and fixing pressure. Namely, styrenes, vinyl esters, esters of α-methylene aliphatic monocarboxylic compounds, acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers, vinyl ketones, rosin-modified phenol-formalin resin, oil-modified epoxy resin, and various epoxy resins. , non-vinyl resins such as non-vinyl thermoplastic resins such as polyurethane resins, cellulose resins, and polyether resins, or mixtures of these and vinyl resins as described above may also be used.

These resins are added in a range of 30% to 60% by weight in the toner in order to improve the pressure fixing or heat fixing properties of the toner, and to adjust the conductivity of the toner as an electrically insulating binder. Added. The greater the amount of resin added, the better the fixing properties of the toner, the lower the electrical conductivity of the toner, and the more the toner can be transferred by an electric field.

The toner particles have the above-mentioned ferromagnetic fine particles and thermoplastic resin as essential components, but may also contain non-magnetic fine particles [A] added to the surface of the toner particles, pigments and dyes that are easily triboelectrically charged, additives, etc. can. Various organic pigments, inorganic pigments, dyes, etc. can be used for these, and dyes are particularly effective. Depending on the purpose, dyes include basic dyes, acid dyes, acid mordant paints,
Metallic dyes, direct dyes, architectural x dyes, sulfur dyes,
There are disperse dyes, naphthol dyes, reactive dyes, onium dyes, oil-soluble dyes, etc., but metal-containing dyes and oil-soluble dyes are effectively used when dispersibility into the toner is considered. Further, as a matter of course, it is necessary to use a dye to be contained in the toner that has a different triboelectrification series from the fine particles [A] in consideration of triboelectric charging with the fine particles [A] added to the surface of the toner. The amount added is at most 3% by weight, and the effect is apparent.

Carbon black, graphite, etc. can be added as conductive fine particles inside the toner particles in order to control the conductivity of the toner. As the amount of these added increases, the conductivity of the toner increases, but the fixing properties of the toner tend to decrease, so the amount of conductive fine particles added inside the toner particles is 10 % or less, preferably 5% or less.

On the surface of the toner particles having the above structure, non-magnetic fine particles [A] which are smaller than the toner particles and can be triboelectrically charged by contact with the toner particles and non-magnetic conductive fine particles [B] are formed. It is added in an amount of 0.01 to 3%, preferably 0.1 to 1% by weight based on the toner particles.

Since the nonmagnetic fine particles [A] are added to the toner particle surface, their average particle size is smaller than the particle size of the toner particles, and particles of about 0.005 to 5 μm can be used, but particles of about 0.005 to 0.1 μm are preferable. good. Fine particles [A] are electrically insulating non-magnetic fine particles,
A material that can be triboelectrically charged upon contact with toner particles is used. Here, it is sufficient that the degree of electrical insulation of the fine particles [A] is 10 ^-7 ·cm ^-1 or less in terms of electrical conductivity.

Many organic and inorganic fine powders can be considered as fine particles having the above average particle size and electrical insulation properties, but when considering triboelectrification with toner materials, that is, resins, magnetic substances, pigments, additives, etc. , the dye fine particles described above are particularly effective. Among dyes, oil-soluble dyes and metal-containing dyes are effective. These dyes themselves have strong polarity and are highly triboelectrically charged, and are triboelectrically charged with various resins, including magnetic powder used in toners, and electrostatically adhere to the toner surface.

In the present invention, the triboelectric polarity of the fine particles [A] with respect to the toner particles may be either positive or negative, based on the principle of the present invention, and it is sufficient that they are triboelectrically charged with the toner particles. However, it needs to be non-magnetic. If it is a magnetic material, it will adhere to the developing magnet roll sleeve due to magnetic force, making it difficult to be held electrostatically on the surface of the toner particles.

Since the non-magnetic conductive fine particles [B] are also added to the surface of the toner particles, their average particle diameter needs to be approximately the same as that of the fine particles [A]. Also,
The higher the conductivity, the better; graphite, carbon black,
A good conductor such as fine metal powder is used. However, as in the case of the fine particles [A], it is necessary that they be non-magnetic.

The amount of fine particles [A] and [B] to be added is, as mentioned above, in the range of 0.01 to 3%, preferably 0.1 to 1%, based on the weight of the toner particles. Below 0.01%,
If this effect is not achieved and the amount exceeds 3%, the proportion of fine particles that are not retained on the toner particle surface and move around freely increases, resulting in fogging on the image. In addition, the conductivity of the toner increases, causing uneven transfer to the transfer sheet, resulting in severe blurring and blurring of the image.

The mixing ratio of the fine particles [A] and [B] is such that the amount of [A] added to the toner particles is greater than or equal to the amount of [B] added. The fine particles [A] can fulfill their role as long as they are triboelectrically charged with the toner particles, but the fine particles [B] need to form a kind of conductive path on the surface of the toner particles and serve as a path for the charge. Therefore, it is thought that it is better to add more amount than the fine particles [A], but because of its conductivity, it is difficult to be electrostatically retained on the surface of the toner particles, and there is a risk that it will be peeled off from the toner particles and stain the image. Therefore, the amount of fine particles [B] added should be equal to or less than that of fine particles [A]. Based on the principle of the present invention, fine particles [A] and [B] are both essential, and if one of them is missing,
The purpose of the present invention cannot be achieved.

Fine particles [A] and [B] exhibit their effects simply by electrostatically adhering them to the surface of the toner particles, but if they are simply electrostatically adhering, they are easier to peel off than the toner particle surface, as described above. This often causes image fog. Therefore, a method can be considered in which part of the fine particles [A] and [B] are fused and fixed onto the surface of the toner particles by heat. The amount to be fixed is a part of the fine particles [A] and [B]. This is because, if all of the fine particles [A] are fixed, the toner particles and [A] will be less likely to rub against each other, and frictional charging development between them will no longer occur. Furthermore, if the surface of the toner particles is entirely covered with the fine particles [B], frictional charging due to the fine particles [A] will no longer occur. Further, the fine particles [B] have the effect of improving the fluidity between the toner particles because a part of them exists in a state where they can move freely between the toner particles. Due to the above circumstances, when fine particles [A] and [B] are fixed on the surface of toner particles, they are added as part of the amount to be added. The amount varies depending on the material used, but it is necessary to ensure that the amount of freely moving fine particles does not become less than 20% of the total.

Next, an example of a method for manufacturing the toner of the present invention will be described.

Grind the resin with a turbo cutter to make it a fine powder. Next, the resin, magnetic powder, and pigment (e.g. carbon black or dye) are weighed and premixed in a super mixer.The mixture is melt-kneaded in a kneader, cooled,
After solidification, it is coarsely pulverized and then finely pulverized to obtain a fine toner powder. The fine toner powder thus obtained is somewhat charged due to the frictive charge generated when the toner is pulverized, and cannot be used as it is because charged agglomeration will occur. Therefore, after adding a small amount of silica powder such as Erosil to improve the fluidity of the toner, we
The toner particles are dropped into a container (180°C) and the toner particles are heated to eliminate the charge caused by toner breakage and prevent the toner from agglomerating.

Next, cut toner with a diameter of 40 μm or more using a high boulder to make the particle size of the heat-treated toner uniform. If most toner particles have a particle size of 40 μm or more, image roughness will become severe. After cutting the toner with a large particle size, add the fine particles [A] and [B] of the present invention, mix well, and cut the toner with a small particle size of 5μ or less using a microbrex, zigzag classifier (Albine, Germany), etc. do. If there is a large amount of toner with a small particle size, the image density will be high, but the image will have a lot of fog. Fine particles [A], [B]
Both are small particles of 5μ or less, but since those attached to the toner particle surface cannot be easily removed by force such as wind force, they can be added before classifying the small particle size toner. . Furthermore, particles that do not adhere to the surface of the toner particles have a negative effect on the image, so they are cut together with the small particle size toner. In this way, the toner of the present invention can be obtained, but it is also effective to add some of the fine particles [A] and [B] to the toner before heat-treating the toner and fuse and fix them on the surface of the toner particles. It is.

The toner of the present invention is a magnetic toner for electric field transfer, and needs to have low electrical conductivity. The electrical conductivity of the toner varies somewhat depending on the type and amount of fine particles [A] and [B] added to the surface of the toner particles.
However, within the range of the amount added according to the present invention, the conductivity of the toner does not exceed 10 ^-7 cm ^-1 .
Electric field transfer of toner is possible. Note that the conductivity of the toner in the present invention is at an electric field of 10,000 V/cm.
The current value was measured under a pressure of 100 g/cm ² and calculated.

Next, a preferred image forming method using the toner of the present invention will be explained.

The electrostatic latent image on the photoreceptor is developed using a developing machine composed of a magnet roll having a magnetic force of 600 to 1000 Gauss. At this time, insert a high resistance element of 1MΩ or more between the conductive sleeve (made of aluminum) of the developing machine and the ground. Alternatively, the conductive sleeve is coated with an electrically insulating material such as polyethylene terephthalate film. The magnetic toner of the present invention is attached to the sleeve of the above-mentioned developing machine,
Magnet roll over 600rpm, sleeve
Rotate at 5 rpm or more to form a toner brush on the sleeve and develop the photoreceptor. The important thing here is to increase the rotation speed of the magnet roll as much as possible. Do not stop the rotation of the sleeve. The most suitable method is to rotate the magnet roll and the sleeve in opposite directions to the rotation direction of the photoreceptor, and to make the number of rotations of the sleeve lower than the number of rotations of the magnet roll. By this method, a photoreceptor can be developed well using the magnetic toner of the present invention, and the developed toner image can be well transferred by electric field to a transfer sheet.

The present invention will be explained below using examples. It is clear to those skilled in the art that the present invention is not limited in any way by the following examples, and that all magnetic toners analogous to or applied to the present invention belong to the present invention.

Example 1 As a fixing resin, 70 parts by weight of polyethylene wax Hiwax 200P from Mitsui Polychemical Co., Ltd. and ethylene-vinyl acetate copolymer from Allied Chemical Co., Ltd. were used.
Weigh out 30 parts by weight of ACP400 and 200 parts by weight of Toda Kogyo's magnetite EPT-500 as magnetic powder.
Dry premix in Supermixer for 5 minutes. Next, the mixture is melt-mixed in a kneader heated to 150° C., and the cooled and solidified product is coarsely and finely pulverized in a turbo mill to obtain fine toner powder. In order to improve the fluidity of the toner, 1.5 parts by weight of silica fine powder R972 from Nippon Aerosil Co., Ltd. is added and mixed well with a super mixer. If the toner remains as it is, it will cause agglomeration due to the electrification during crushing, resulting in poor fluidity. Therefore, the toner is dropped through a heating furnace heated to 100 to 180° C. to eliminate the fringe charge on the toner and further improve its fluidity.

Next, according to the present invention, Mitsubishi Chemical's Carbon Black #44 (PH7.5) with an average particle size of 0.021 μm and metal-containing or oil-soluble dye fine powder with an average particle size of 0.1 μm or less are added to the toner as conductive fine particles. Add and mix.
The amount of carbon black added is 0.2% by weight based on the total weight of the toner, and the amount of dye added is 0.2% by weight based on the total weight of the toner.
The content shall be 0.2% by weight. After adding carbon black and dye to the toner and mixing them thoroughly, the toner was passed through an Albine zigzag classifier 100MZR for 10 minutes.
Classify to ~20 μm.

As described above, the magnetic toner of the present invention is prepared.
Like 3820, we used the company's oil-soluble dyes, such as Special Black EB, Oil Black BS, BY, and Nigrosine Base EX. According to Toshiba Electric's blow-off powder charge measuring device, the frictional charge amounts of these dyes with the iron powder carrier are -12.4μC/g, -21.0μC/g, and -21.0μC/g, respectively, in the order in which the dyes are listed together. −
20.7μC/g, +43.6μC/g, +6.8μC/g, +
10.8μC/g, +18.7μC/g.

When the conductivity of the toner thus prepared was measured using the method of the present invention described above, it was found to be 10 ^-8 to ^{10 -11} cm.
It was ^-1 . Therefore, it was found that electric field transfer of toner to a transfer sheet is possible.

Next, the toner was deposited on the developing magnetic roll sleeve, and the image of the toner was evaluated.
The developing magnet roll has 12 magnetic poles made by Hitachi Metals.
The pole has a magnetic force of 600 Gauss. The sleeve is an aluminum conductive sleeve, and a 10MΩ electrical resistor was attached between the sleeve and ground.
The sleeve and magnet roll of the above developing machine are rotated at 20 rpm each in the opposite direction to the moving direction of the photoreceptor.
The zinc oxide or selenium photoreceptor with the electrostatic latent image was developed by rotating at 12,000 rpm. For development,
A copying machine using a zinc oxide photoconductor was a Sharp SF-730, and a copying machine using a selenium photoconductor was a Xerox Co. 2200, and each was equipped with the above-mentioned developing device to produce images. was prepared.

When a recording paper having a volume resistivity of 10 ¹⁴ cm or more, such as H20 paper from Nippon Pulp Co., Ltd., was used as the transfer paper, good transferred images were obtained with the toner of the present invention. In addition, the transferred image was well fixed on the paper surface by the pressure roll, and the image had good halftone reproducibility, making it possible to obtain a copy similar to conventional two-component toner.

Example 2 As the fixing resin, an epoxy resin manufactured by Ciel Kagaku Co., Ltd., Epikote #1004 and #2057 in a mixing ratio of 3:2 was used, and as the magnetic powder, Magnetite KN-320 manufactured by Toda Kogyo Co., Ltd. was used. A magnetic toner was prepared and evaluated in exactly the same manner. As a result, a good transferred image could be obtained using a toner prepared by mixing the same carbon black and dye as in Example 1, and the image could be transferred by heating it for 5 seconds in an oven heated to 150°C. The resistance was well established.

Example 3 As the fixing resin, Sanyo Chemical's styrene resin,
A magnetic toner was prepared and evaluated in exactly the same manner as in Example 1 using Higher ST-120 and Toda Kogyo's Magnetite EPT-500 as the magnetic powder.
As a result, a good transferred image could be obtained using a toner prepared by mixing the same carbon black and dye as in Example 1, and the image was well fixed on the paper surface by a heat roll heated to 180°C. It was done.

Example 4 A developing sleeve was covered with a Teijin polyethylene terephthalate film to provide electrical insulation.
Using this developing machine and the magnetic toners listed in Examples 1 and 3, a magnetic toner transfer image was produced in the same manner as in Example 1, and as a result, a good transfer image was obtained.

Example 5 In Examples 1 to 3, 1 part by weight of Oil Black BY was added as a dye inside the magnetic toner,
Examples 1 to 3 include carbon black on the outside of the toner and Varifast Black 3804 as a dye.
A magnetic toner was prepared by adding in the same manner as above. When the toner was evaluated in the same manner as in Example 4, a good transferred image was obtained. As described in Example 1, the amount of charge of the dye used here is +10.8 μC/by as the amount of friction charge with the carrier.
g, Barrier First Black 3804 is -12.4μC/g
, and the positive and negative polarities are opposite to the carrier. It is thought that because the triboelectrification series of the dyes were different, a large amount of triboelectricity was generated on the surface of the toner particles, increasing the amount of charge on the toner, and resulting in a good transferred image.

Example 6 In Example 5, toners were prepared by changing the types of dyes added to the inside and outside of the magnetic toner, and evaluated in the same manner. As a result, even when the dye type was changed, a good transferred image could be obtained in exactly the same way.

Example 7 In the toners of Examples 1 to 6, an amount corresponding to 50% of the carbon black and dye added to the outside of the toner was added to the toner before it was dropped into a heating furnace, and thoroughly stirred with a super mixer.
Mixed. After mixing, the toner was dropped into a heating furnace, and 50% of the added carbon black and dye were fused and fixed on the surface of the toner particles. The toner thus prepared had less image fogging, that is, less background smearing than the toners in Examples 1 to 6, and good image characteristics were obtained.

Comparison row 1 In the toners of Examples 1 to 7, toners were prepared in which only one of carbon black or dye was added to the surface of the toner particles. With the prepared toner, the density of the transferred image was low and the image was uneven.
It was found that it was difficult to put it into practical use due to poor image characteristics.

Claims (1)

[Scope of Claims] 1. A magnetic toner for developing an electrostatic latent image comprising toner particles containing at least ferromagnetic fine particles and a thermoplastic resin, wherein the toner particles have on their surfaces a bond with the toner particles smaller than the toner particles. Non-magnetic fine particles [A] that can be triboelectrified by contact and non-magnetic conductive fine particles [B] are added in an amount such that [A] is equal to or more than [B] in terms of weight relative to the toner particles.
A magnetic toner for developing an electrostatic latent image, characterized in that it is retained at a ratio of 0.01 to 3%. 2. In the magnetic toner for developing electrostatic latent images according to claim 1, fine particles of a metal-containing dye or oil-soluble dye are used as the non-magnetic fine particles [A], and carbon black is used as the non-magnetic conductive fine particles [B]. A magnetic toner characterized by using fine particles of. 3. In the magnetic toner for developing electrostatic latent images according to claim 1, a part of the non-magnetic fine particles [A] and the non-magnetic conductive fine particles [B] are fused and fixed on the surface of the toner particles. Features magnetic toner.